Hi,
after compiling and testing the library DirectFB (directfb.org) I
figured out some annoying effect concerning the ABI.
DirectFB uses some sort of interface which can be summarized as:
-------------------------
void f(int a, int b, int c){/*Do something with a,b and c*/}
typedef void (*Genericf)(int a, ....);
Genericf g = (Genericf)f;
g(1, 2, 3); // <- Crash on OpenRISC because of different calling
conventions for variadic functions.
-------------------------
As far as I know there is nothing written in the C specification which
says, that this should work.
So I don't blame that the OpenRISC ABI is wrong. I think that DirectFB
makes a terrible design decision.
That they claim, there software is for embedded systems makes it even worse.
But it seems that especially the ABIs of x86 and ARM are defined in a
way that makes this possible.
I have not checked the others architectures.
If I don't get any objection about the fact I will send some similar
mail to the DirectFB mailing list.
I hope that this is the only library which is using such a design.
Otherwise I would suggest to change the OpenRISC ABI.
Unfortunately it seems that DirectFB will not compile correctly on
OpenRISC without a substantial change in the source code.
Sebastian
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